Soybean (Glycine max L.) production often experiences constraints from drought stress, which significantly reduces yield in tropical areas. The pdh1 gene, known to support pod-shattering resistance, has shown significant potential for enhancing drought tolerance. Therefore, this study aimed to examine the performance of tropical soybean genotypes carrying the pdh1 gene in response to drought stress during flowering to pod formation. A randomized complete block design with factorial arrangement had three replications. The factors included 25 genotypes and two water supply treatments. The water supply treatment consisted of D0=±80% and D1=±50% field capacity (FC), corresponding to soil water potentials of -0.47 and -1.42 MPa, respectively. The yield-related traits’ analysis used 15 drought tolerance indices. The results showed AP21 and AP46 lines with the pdh1 gene were considerably high-yielding and drought-tolerant genotypes. Substantial associations of yield in stress (Ys) and normal condition (Yn) were evident between genotypes with high geometric mean production (GMP), mean production (MP), stress tolerance index (STI), yield index (YI), and low stress susceptibility index (SSI). The results showed genotypes carrying the pdh1 gene can potentially increase drought tolerance in soybeans. The high yield under drought primarily referred to better retention of pod numbers, seed numbers, and seed size.
Soybean (G. max L.), water deficit conditions, long juvenile, seed yield, drought tolerance indices, reproductive stages
Soybean (G. max L.) genotypes carrying the pdh1 gene showed the highest potential for enhancing drought tolerance in soybeans. Principal component and biplot analyses confirmed that indices, such as high GMP, high MP, STI, and YI, and low SSI, emerged as effective measures for selecting high-performance genotypes under drought stress conditions.